67 lines
2.4 KiB
Lua
67 lines
2.4 KiB
Lua
-- httpserver-connection
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-- Part of nodemcu-httpserver, provides a buffered connection object that can handle multiple
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-- consecutive send() calls, and buffers small payloads to send once they get big.
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-- For this to work, it must be used from a coroutine and owner is responsible for the final
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-- flush() and for closing the connection.
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-- Author: Philip Gladstone, Marcos Kirsch
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BufferedConnection = {}
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-- parameter is the nodemcu-firmware connection
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function BufferedConnection:new(connection)
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local newInstance = {}
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newInstance.connection = connection
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newInstance.size = 0
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newInstance.data = {}
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function newInstance:flush()
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if self.size > 0 then
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self.connection:send(table.concat(self.data, ""))
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self.data = {}
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self.size = 0
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return true
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end
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return false
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end
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function newInstance:send(payload)
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local flushthreshold = 1400
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local newsize = self.size + payload:len()
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while newsize > flushthreshold do
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--STEP1: cut out piece from payload to complete threshold bytes in table
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local piecesize = flushthreshold - self.size
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local piece = payload:sub(1, piecesize)
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payload = payload:sub(piecesize + 1, -1)
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--STEP2: insert piece into table
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table.insert(self.data, piece)
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self.size = self.size + piecesize --size should be same as flushthreshold
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--STEP3: flush entire table
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if self:flush() then
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coroutine.yield()
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end
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--at this point, size should be 0, because the table was just flushed
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newsize = self.size + payload:len()
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end
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--at this point, whatever is left in payload should be <= flushthreshold
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local plen = payload:len()
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if plen == flushthreshold then
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--case 1: what is left in payload is exactly flushthreshold bytes (boundary case), so flush it
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table.insert(self.data, payload)
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self.size = self.size + plen
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if self:flush() then
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coroutine.yield()
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end
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elseif payload:len() then
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--case 2: what is left in payload is less than flushthreshold, so just leave it in the table
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table.insert(self.data, payload)
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self.size = self.size + plen
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--else, case 3: nothing left in payload, so do nothing
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end
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end
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return newInstance
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end
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return BufferedConnection
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